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Academic literature on the topic 'Interactions hôte-agent pathogène'
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Journal articles on the topic "Interactions hôte-agent pathogène"
Khau, Sandra, and Cassandra Lopatynski. "Les génomes viraux défectueux du virus Chikungunya: Vers une nouvelle approche d’antiviraux à large spectre ?" médecine/sciences 38, no. 11 (November 2022): 955–59. http://dx.doi.org/10.1051/medsci/2022141.
Full textSoulie, Marie-Christine, Brigitte Vian, and Thérèse Guillot-Salomon. "Interactions hôte–parasite lors de l'infection par Cercosporella herpotrichoides, agent du piétin-verse : morphologie du parasite et ultrastructure des parois d'hôtes sensibles et résistants." Canadian Journal of Botany 63, no. 5 (May 1, 1985): 851–58. http://dx.doi.org/10.1139/b85-110.
Full textDissertations / Theses on the topic "Interactions hôte-agent pathogène"
Cellier, Mathieu. "Elaboration de modèles expérimentaux pour l'étude des stress cellulaires dans les interactions hôte - agent pathogène." Montpellier 2, 1992. http://www.theses.fr/1992MON20205.
Full textAyach, Maya. "Interaction hôte-pathogène : mécanisme d’inhibition de la synthèse protéique humaine par la protéine circumsporozoïte de Plasmodium falciparum, agent du paludisme." Strasbourg, 2011. http://www.theses.fr/2011STRA6100.
Full textDuring my PhD, I was concerned by the study of the host-parasite interaction and its consequences on protein synthesis in human and Plasmodium falciparum (parasite responsible of the malaria) respectively. I have developed two major aspects : (i) The study of the aminoacylation reaction of transfer RNA and thus by comparison of human and parasite systems and (ii) the understanding of the mechanism of inhibition of protein synthesis in human by the Circumsporozoite protein of the parasite, a transmembrane protein which is secreted during the parasite infection of host hepatocytes. The plasmodial cytosolic tyrosyl-tRNA synthetase is a classical synthetase concerning its structural organization. It possesses two functional domains, catalytic domain and tRNA binding one. The kinetic characteristics of the aminocylation reaction (Km, Kcat and plateau) were determined. I have clearly shown that plasmodial TyrRS animoacylates both transcripts of plasmodial and human tRNATyr with the same efficiency. On the other hand, only a small fraction of modified human tRNATyr was aminoacylated by the parasite enzyme. These results indicate that crossaminoacylation reactions between the parasite and human are possible, but their efficiency varies from one system to another. Concerning the apicoplastic TyrRS, this enzyme, at the opposite of the cytosolic one, it presents two insertions. These insertions are characteristic of some parasite proteins and are called LCR (Low Complexity Region). The presence of such sequences in the apicoplastic TyrRS but also in other parasite proteins makes their expression in heterologous systems a difficult obstacle in the study of the parasite. During my PhD work, I did participate to the collaboration of a new hypothese concerning the function and the role of these insertions in the production of soluble proteins. These LCRs play a key role in the co-translational folding of the parasite proteins. Finally, the big part of my work concerns the study of consequence of the host-parasite interactions on protein synthesis in human liver cells during the hepatic stage of the infection. During this stage, the parasite is covered by a transmembrane protein called the Circumsporozoite protein (CSP). Previous study in 1997 showed that CSP is secreted by the parasite, and co-localizes with endoplasmique reticulum where it does probably inhibit host translation. I have demonstrated by using rabbit reticulocytes lysate, that CSP inhibits efficiently translation and that by inhibiting the formation of pre-initiation complex 48 S. This inhibition involves a direct interaction between the CSP and the small ribosomal particle 40 S. This work shows for the first time that parasites, like some virus, could affect directly host protein synthesis. My work is part of large project concerning the study of hepatic stage of the infection; in this manuscript I will discuss the role and the consequences of such translation inhibition on the parasite life cycle
Duperret, Léo. "Caractérisation des mécanismes moléculaires de la permissivité au Syndrome de Mortalité de l'Huître du Pacifique (POMS) sous influence de la température et du régime alimentaire." Electronic Thesis or Diss., Perpignan, 2024. http://www.theses.fr/2024PERP0042.
Full textOver the past decades, food production systems have had to meet the growing demand for food driven by the exponential increase in the global human population. This demand has led to intensified agriculture, livestock farming, and fishing practices, often at the expense of natural resources and planetary health. In the marine environment, intensified fishing has resulted in the depletion of certain stocks and the implementation of fishing quotas. The decline in marine resources has prompted the development of aquaculture, a practice for farming blue resources. However, with overproduction and global environmental changes, we have witnessed an upsurge in epizootics since 1970, particularly among ectothermic organisms. The Pacific Oyster Mortality Syndrome (POMS) is a prime example, responsible for significant annual mortality episodes in juvenile oysters of the species Magallana gigas across major producing countries. Emerging in 2008 in France, this polymicrobial disease is influenced by several factors, including temperature (between 16°C and 24°C along the French coasts) and the availability of nutritional resources. Although extensive research has helped characterize its pathogenesis and identify the various factors influencing the development of the disease, the molecular mechanisms underlying variations in permissiveness according to these factors remain largely unknown. This thesis addresses this objective. Through a rigorous experimental design, a holistic approach, and an integrative comparative analysis at multiple scales under permissive and non-permissive conditions for the disease, we identified the molecular mechanisms underlying permissiveness related to temperature and nutritional resources. These findings enhance our understanding of the complexity of host-pathogen-environment interactions and will ultimately contribute to the development of predictive models for epidemiological risk
Durand, Tristan. "Interactions virales chez l'abeille mellifère (Apis mellifera) et conséquences sur leur santé." Electronic Thesis or Diss., Université Côte d'Azur, 2024. http://www.theses.fr/2024COAZ6041.
Full textHoney bees (Apis mellifera) are frequently infected by multiple viruses. While most of them remain commensal, some can become pathogenic in specific contexts. Deformed wing virus (DWV), sacbrood virus (SBV), acute (ABPV) and chronic (CBPV) bee paralysis viruses infections can notably lead to overt infections in honey bee brood and/or adults and participate to the collapse of colonies. The multiple factors promoting active replication of these viruses and the apparition of diseases are however not well known. However, synergistic and inhibitory effects are known to appear through interactions between co-infecting viruses and between viruses and their hosts. The honey bee immune system, through its activation or inhibition triggered by some viruses, may be crucial in the emergence of interactions between viruses. Despite this, viral infections in honey bees are still mostly studied in cases of single infection. Thus in this work, I experimentaly studied the effects of co-inoculations in two pairs of viruses. On one hand I examined the effects of DWV and SBV co-inoculations, two viruses belonging to the same viral family, on the apparition of clinical signs, the mortality, the behaviour as well as the expression of multiple immune genes. In these experiments, variation of various factors were tested : the inoculated viral strains, the developmental stage of honey bees, the inoculation method and the chronology of infection. On the other hand, I studied the effects of ABPV and CBPV co-inoculation, two viruses belonging to different viral families but inducing similar pathologies. Here, the quantity of inoculated virus seemed crucial in determining how the two viruses could interact. This work reveals the existence of multiple interactions between different honey bee viruses, shows the importance of paying attention to the presence or absence of multiple pathogens and, in general, incites more systematic and holistic research methods in the field of honey bee pathology
Dong, Jiawei. "Etude in vitro des interactions entre la protéine NS1 du virus respiratoire syncytial et la sous-unité MED25 du Médiateur humain." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASQ077.
Full textRespiratory syncytial virus (RSV) is a major cause of severe respiratory infections, particularly in infants and young children. It evades the innate immune system notably thanks to its two non-structural proteins, NS1 and NS2. The NS1 protein functions as an interferon antagonist, inhibiting both the production of interferons and their signaling pathways. However, a new hypothesis suggests that NS1 could also contribute to the regulation of host gene expression via an interaction with the MED25 subunit of the mediator complex, a coactivator of transcription by RNA polymerase II. My thesis focuses on the structural characterization of this interaction in vitro.In a first step, I wanted to ensure that NS1 was in its native form under the conditions used for interaction experiments. NS1 can indeed be produced as a recombinant protein in E. coli, and a crystallographic structure of NS1 is available: it reveals a globular domain "NS1core" and a C-terminal helix "NS1α3" located at the interface of an NS1 dimer. However, NS1 is challenging to study in solution due to its propensity to self-assemble. I thus analyzed the behavior of NS1 under different experimental conditions and by different biophysical techniques: differential scanning fluorimetry to assess stability, circular dichroism to assess secondary structure, and light scattering to assess size. This allowed providing evidence for an NS1 monomer-dimer equilibrium. A deletion mutant of NS1, NS1∆α3 corresponding to NS1core, was amenable to nuclear magnetic resonance (NMR) for structural analysis at the single residue scale. I performed backbone assignment, and showed that it was well folded in solution. Large line-widths and 15N relaxation measurements pointed at exchange phenomena. Assignment of NS1∆α3 then permitted to partially assign full-length NS1 and to analyze NMR interaction experiments.The second part of my thesis focuses on the interaction between NS1 and the ACID domain of MED25. NMR studies using 15N- and 13C-labeled MED25-ACID protein and a peptide corresponding to NS1α3 first revealed that NS1α3 interacts with MED25-ACID. Additionally, calorimetry experiments showed that full-length NS1 had a much higher affinity than NS1α3, suggesting a potential interaction via the globular NS1core domain in addition to the NS1α3 helix. Data obtained from biolayer interferometry (BLI) then confirmed this interaction. These data showed that NS1∆α3 binds to MED25-ACID with lower affinity than NS1, exhibiting two binding modes. AlphaFold2 modeling did not produce reliable complex models with NS1∆α3 or NS1α3. But it allowed reasonably accurate prediction of the structure of the MED25-ACID−NS1 complex. NS1 mutants based on this prediction were tested by BLI, showing a reduction in interaction with MED25-ACID
Loison, Lea. "Rôle des interactiοns hôte-micrοbiοte dans la physiοlοgie intestinale et dans les Τrοubles du Cοmpοrtement Alimentaire." Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMR049.
Full textThe gut microbiota constantly interacts with the host. It communicates directly with neighboring intestinal cells as well as with distant organs, including the brain. As a result, the microbiota regulates numerous biological processes and is involved in the pathophysiology of many diseases.We first investigated whether commensal bacteria from the gut microbiota modulate an essential post-translational modification in intestinal physiology, i.e. SUMOylation. It has been demonstrated that gut commensal bacteria can promote SUMOylation through the production of short- and branched-chain fatty acids (SCFA/BCFA). In the present study, we demonstrated that the commensal bacterium Staphylococcus warneri secretes a protein, named Warnericin RK, which targets key components of the SUMOylation machinery, leading to a decrease in intestinal cell’s SUMOylation. This decrease in SUMOylation promotes gut inflammation, and more particularly TNF-dependent inflammatory responses. Collectively, these findings highlight the versatility of mechanisms used by non-pathogenic bacteria in the gut microbiota to regulate host SUMOylation. Additionally, they show that changes in the composition of the gut microbiota may have an impact on gut inflammation by modulating the equilibrium between bacterial effectors enhancing or suppressing SUMOylation.Secondly, we investigated the role of the gut microbiota in the pathophysiology of Binge-Eating Disorder. Indeed, the microbiota is involved in the regulation of eating behaviors through communication along the gut-brain axis. Consequently, it has been hypothesized that the microbiota may be a contributing factor to binge-eating disorder. To investigate the potential causal role of the gut microbiota in this disease, we have transplanted fecal microbiota from patients to recipient mice. Our experimental model did not allow us to demonstrate a role for the microbiota in changes in eating behavior, or in the gastrointestinal and anxiety-depressive disorders associated with binge-eating disorder
He, Le. "Interactions hôte-pathogène entre Caenorhabditis elegans et le champignon Drechmeria coniospora." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4080/document.
Full textWe have successfully adapted a PEG-mediated transformation protocol for D. coniospora. Together with the ccdB and Gibson based plasmid construction method, we established a system to genetically manipulate this fungus which serves as an important tool for host-pathogen interaction study. We identified the specific pathogenic lifestyle of D. coniospora based on its genomic sequence. Comparative genomic analysis revealed a list of potential fungal effectors which engage with the host immunity, for instance SapA (G3895). We further constructed a reporter strain for SapA and identified its host target SPP-5, an antimicrobial peptide. Our study focusing particularly on the pathogen provides an insight for the host-pathogen interaction between C. elegans and D. coniospora. Despite the successful generation of 5 D. coniospora transgenic strains. Nevertheless, the remaining problems such as multiple transferring during protoplasts preparation and slow growth of D. coniospora after transformation still need to be resolved. One of the solutions is to substitute the general medium with a medium resembling the host environment.We show that D. coniospora SapA protein interacts with worm immune effector, SPP-5 in vitro indicating its potential role to suppress the host immunity. Due to the fact that SapA is also highly expressed at the late stage of infection, we cannot rule out the other possible functions of this protein. We could employ Mass spectrometry technique to identify other host proteins which interact with SapA in vivo
Brax, Sylvain. "Rôle du cytosquelette de septines dans les infections bronchiques à Pseudomonas aeruginosa dans le contexte de la mucoviscidose." Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS309.
Full textBronchial epithelial cells form a physical barrier against inhaled pathogenic microorganisms and coordinate the immune responses of the lung. However, in the context of cystic fibrosis (CF), impairment of the mucociliary clearance process and the immune response favours colonisation of patients' bronchi by the bacterium Pseudomonas aeruginosa. The repetition of infection/inflammation cycles induces lesions in this bronchial epithelium, leading to a decline in patients' respiratory function, the leading cause of patient mortality. It is therefore crucial today to identify new molecular cellular players involved in the host response. In this study, we focused on the septin cytoskeleton (SEPT) which has been shown to be important in host-pathogen interactions and in the maintenance of barrier function. We first demonstrated the central role of SEPT7 in the maintenance of the SEPT cytoskeleton. But also, for the formation of cage-like structures around intracellular P. aeruginosa. We have also shown that SEPT2, SEPT7 and SEPT9 are involved in the response of the bronchial epithelium to infections. They participate in a process aimed at limiting the number of intracellular P. aeruginosa and modulate IL-6 cytokine secretion following infection by this pathogen. However, this SEPT-dependent response is impaired in the CF context, which could explain the persistence of P. aeruginosa infections in the pathology. Finally, we observed that pre-treatment with CFTR modulators did not restore these processes, suggesting that the CFTR protein is not directly involved. A better understanding of the role played by the SEPT cytoskeleton in the response of the bronchial epithelium to CF and non-CF infections could lead to the development of new therapeutic approaches to combat pathogens such as P. aeruginosa
Burette, Mélanie. "Etude de la réplication intracellulaire et de la persistance de Coxiella burnetii, agent pathogène de la Fièvre Q." Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTT053.
Full textIntracellular replication and persistence strategies of the Q fever pathogenCoxiella burnetiiCoxiella burnetii is the causative agent of human Q Fever, considered as one of the most relevant re- emerging zoonosis in Europe. C. burnetii infects humans through the inhalation of contaminated aerosols, causing epidemics with serious economic and health consequences. Following internalisation, C. burnetii subverts host cell functions to inhibit the innate immune response and generate a replicative niche called CCV (Coxiella-containing vacuole) characterised by a unique protein and lipid composition. My thesis project focuses on the study of the host/pathogen interactions underlying the persistence and intracellular replication of C. burnetii.First, the function of the effector protein NopA was discovered showing how this protein inhibits the innate immune response in infected cells. The results obtained during my PhD have shown that NopA interacts with Ran and triggers an imbalance in its nucleocytoplasmic gradient, thereby perturbing the nuclear import of eukaryotic proteins and the expression of pro-inflammatory cytokines. In parallel, the role of lipid metabolism in the establishment of the CCV was investigated. By using a wide array of lipid probes and confocal microscopy, the lipid signature of CCVs was determined and revealed that PI(4)P and LBPA are actively subverted by C. burnetii during infection. Lipid pulldown assays then led to the identification of C. burnetii candidate effector proteins interacting with host cell lipids. One of them, CBU0635, is a putative phosphoinositide phosphatase that diverts the secretory pathway to the forming Coxiella- containing vacuole while CBU2007 manipulates lysobisphosphatidic acid metabolism to recruit the ESCRT machinery and block the biogenesis of multivesicular bodies. These results help to better understand intracellular replication and persistence strategies of C. burnetii and could allow the development of new antimicrobials and the therapeutic repurposing of C. burnetii proteins
Cesbron, Sophie. "Interaction entre des mutants hrp d'Erwinia amylovora, agent du feu bactérien, le parent pathogène et la plante hôte : recherche de mécanismes modulant la compatibilité." Phd thesis, Université d'Angers, 2009. http://tel.archives-ouvertes.fr/tel-00455109.
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